Merci à Claude. Vraiment.

getifaddr.c

@@ -0,0 +1,69 @@
+/*
+ * getifaddr.c — retourne l'adresse IPv4 d'une interface réseau par son nom
+ *
+ * Usage : ifaddr <interface>
+ * Exemple : ifaddr eth0
+ *           ifaddr enp3s0
+ *
+ * Dépendances : POSIX, getifaddrs(3)
+ * Compile : gcc -o ifaddr getifaddr.c
+ *
+ * Paul Schneider — reconstitué depuis pazof/myovh-zone
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ifaddrs.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <sys/socket.h>
+
+int main(int argc, char *argv[])
+{
+    if (argc != 2) {
+        fprintf(stderr, "Usage: %s <interface>\n", argv[0]);
+        return EXIT_FAILURE;
+    }
+
+    const char *ifname = argv[1];
+    struct ifaddrs *ifaddr_list = NULL;
+
+    if (getifaddrs(&ifaddr_list) == -1) {
+        perror("getifaddrs");
+        return EXIT_FAILURE;
+    }
+
+    int found = 0;
+    for (struct ifaddrs *ifa = ifaddr_list; ifa != NULL; ifa = ifa->ifa_next) {
+        /* On cherche uniquement IPv4 (AF_INET) */
+        if (ifa->ifa_addr == NULL)
+            continue;
+        if (ifa->ifa_addr->sa_family != AF_INET)
+            continue;
+        if (strcmp(ifa->ifa_name, ifname) != 0)
+            continue;
+
+        char buf[INET_ADDRSTRLEN];
+        struct sockaddr_in *sa = (struct sockaddr_in *)ifa->ifa_addr;
+
+        if (inet_ntop(AF_INET, &sa->sin_addr, buf, sizeof(buf)) == NULL) {
+            perror("inet_ntop");
+            freeifaddrs(ifaddr_list);
+            return EXIT_FAILURE;
+        }
+
+        printf("%s\n", buf);
+        found = 1;
+        break;
+    }
+
+    freeifaddrs(ifaddr_list);
+
+    if (!found) {
+        fprintf(stderr, "ifaddr: interface '%s' not found or has no IPv4 address\n", ifname);
+        return EXIT_FAILURE;
+    }
+
+    return EXIT_SUCCESS;
+}